The preset invention relates to an expansion joint device connected to piping or equipment and the like that absorbs the expansion and contraction in the longitudinal axial direction and the displacement in the direction orthogonal to the axis thereby protecting the piping system, and especially to an expansion joint device constituting a part of a passage for transmitting fluid that disfavors contamination or quality deterioration, such as drugs, fluid-state food and drinks, and fluid for electronic components.
Heretofore, expansion bend pipe (tako-bend), bellows (waveform) pipe, slip pipe and the like are known as examples of this type of expansion joint device. The latter two of the examples, the bellows pipe and the slip pipe, characterize in that the distance between the connecting surfaces at the ends of a connecting passage, such as a flange, can be very small.
The problem with the bellows pipe is that when fluid including slurry or fluid having high viscosity travels inside the bellows, impurities enter into the grooves of the bellows, making it impossible for the bellows to perform its primary role, which is to expand, and in cases even lead to breakage of the bellows pipe.
In the attempt to solve the above problems, Japanese Utility Model Laid-Open No. 2-6892 discloses a double (interior and exterior) bellows pipe, the interior bellows pipe being a molded bellows, or Japanese Utility Model Publication No. 49-9776 discloses a bellows pipe equipped with a cylindrical cloth mounted to the interior of the pipe.
According to the disclosure of the former document, though impurities do not easily get caught in the grooves on the inner peripheral surface of the molded bellows, the fluid traveling therein tends to reside in the pipe, causing multiplication of bacteria which is insanitary and could not be applied for drugs or food and drinks. Moreover, if impurity resides in the bellows, the fluid may be contaminated or deteriorated, and therefore it can only be used with limitation for fluid used for electronic components and the like.
According to the latter disclosure, the cylindrical cloth prevents impurities from contacting the inner surface of the bellows, but the fluid removed of the impurities will penetrate through the cylindrical cloth having fluid permeability and reaches the interior surface of the bellows, so the problems related to the bellows pipe mentioned above still exists.
On the other hand, in the case of the slip pipe, the eternal surface of the inner pipe may contact the atmosphere and bacteria may enter the inner pipe via the slide surface between the outer pipe, which generates an insanitary environment.
The present invention aims at solving the above-mentioned problems of the conventional expansion joint device having relatively small distance between connecting surfaces, and to provide an expansion joint device that is especially hygienic and enables to maintain the quality of the fluid traveling inside.
In order to achieve the above objects, the present invention provides an expansion joint device comprising:
a pair of connecting passage end regions equipped to both axial ends;
an expansion outer cylinder capable of axial expansion and contraction, with one axial end region thereof substantially connected in a leakproof manner to one of the connecting passage end regions and the other axial end region thereof substantially connected in a leakproof manner to the other of the connecting passage end regions; and
a cylindrical resin film having no permeability to fluid flowing therethrough, which is substantially cocentrically arranged within the interior of the expansion outer cylinder with one axial end thereof substantially connected in a leakproof manner to one of the connecting passage end regions and the other axial end thereof substantially connected in a leakproof manner to the other of the connecting passage end regions, the cylindrical intermediate region of the cylindrical resin film being arranged to cover the inner surface of the expansion outer cylinder in a leakproof manner.
According to the present invention, no matter whether the expansion outer cylinder is formed as a bellows pipe or a slip pipe, the cylindrical resin film prevents the fluid travelling therethrough from directly getting into contact with the inner surface of the expansion outer cylinder. Therefore, the present invention enables to provide an expansion joint device with an expansion outer cylinder shaped and structured to provide advantageous sanitariness and quality maintaining properties of the fluid flowing therethrough.
The cylindrical resin film is not made of material having fluid permeability such as cloth, but is made of material having no fluid permeability, and may if necessary have elasticity, and should preferably be heat resistant if the fluid traveling through the device must be sterilized using heat.
The actual examples of the cylindrical resin film include silicon, rubber and the like.
The elastic property of the cylindrical resin film is determined appropriately considering the expansion level of the expansion joint device, the tension-resistant power of the cylindrical resin film, the axial stress, and so on. There is also a need to appropriately select the elasticity level of the cylindrical resin film according to the structure of the expansion outer cylinder or the pressure of the flowing fluid. These elements of selection are appropriately determined according to the structure of the expansion joint device and the environment to which it is applied.
It is preferable that the cylindrical resin film is provided with axial pretension. This is to prevent generation of unevenness in the inner surface of the cylindrical resin film due to laxness of the film caused when the expansion joint device is contracted to its minimum length in the axial direction.
In the above invention, the state where the axial end regions of the cylindrical resin film is substantially connected to the connecting passage end regions refers not only to direct connection of the film ends to the connecting passage end regions by welding or bonding, but also to the film ends to be inserted and sandwiched between the connecting passage end region and another connecting member adjacent thereto.
The expansion outer cylinder can either be a prior-art metallic bellows-type outer cylinder, or may be formed of Teflon. In this case, the cylindrical resin film is mounted to the inner side of the bellows-type outer cylinder, and both axial ends thereof are connected to the connecting passage end regions respectively in a leakproof manner.
According to this aspect of the invention, the cylindrical resin film guides the flow of fluid smoothly, and no fluid flows into the grooves formed to the inner surface of the bellows, thereby preventing residence of fluid in the grooves and further preventing deposition of impurities.
Moreover, a plural number of low-hardness elastic resin filling rings may be filled to the spaces defined by grooves formed to the inner peripheral surface of the bellows-type outer cylinder, the inner peripheral surfaces of the rings being connected to form a substantially cylindrical surface. The elastic resin filling rings can be ring-shaped low-hardness elastic resin filling rings that are fit to the grooves formed to the inner surface of the bellows-type outer cylinder, or they can be nonrigid resin filled to the grooves and left for a predetermined time to set.
Accordingly, irrespective of the hardness or the elasticity of the cylindrical resin film, the inner surface of the bellows-type outer cylinder is formed smoothly in a substantial cylindrical shape, so even when the cylindrical resin film expands by fluid pressure, the film will be supported by this smooth cylindrical inner surface, and therefore, the cylindrical resin film will define a smooth inner surface without any residence space for the fluid. Therefore, the sanitariness and the quality of the fluid are maintained.
The plural elastic resin filling rings may be connected and formed integrally, thereby constituting a substantially smooth cylindrical inner surface. This decreases the number of necessary components.
In another aspect of the invention, in addition to the bellows-type outer cylinder, a cylindrical metal sleeve that is cocentrically arranged within the interior of the bellows-type outer cylinder may be applied to the structure. In this case, the cylindrical metal sleeve has one axial end thereof connected to one of the connecting passage end regions in a leakproof manner, the cylindrical resin film having one axial end thereof substantially connected in a leakproof manner to the other free end of the cylindrical metal sleeve and the other axial end thereof substantially connected in a leakproof manner to the other of the connecting passage end regions, the cylindrical resin film together with said cylindrical metal sleeve being arranged to cover the inner surface of the bellows-type outer cylinder in a leakproof manner.
This feature enables a secure protection of the bellows-type outer cylinder by the cylindrical metal sleeve and the cylindrical resin film formed to cover the interior thereof, and further, the expansion and contraction of the bellows-type outer cylinder is absorbed by the expansion and contraction of the cylindrical resin film. Accordingly, the cylindrical metal sleeve provides inner-surface protection of the bellows-type outer cylinder and a smooth guide to the traveling fluid, and therefore enables to reduce the amount of usage of the cylindrical resin film. Further, the elastic resin filling rings can be omitted according to this feature.
In order to prevent expansion of the bellows-type outer cylinder in the radial direction, it is preferable to provide reinforcement rings positioned to the groove regions formed to the outer circumferential surface of the bellows-type outer cylinder. Especially, the effect of providing reinforcement rings is apparent when the bellows is made of polytetrafluoroethylene.
In another aspect of the invention, the expansion outer cylinder may comprise an inner sleeve and an outer sleeve, the axial inner ends of said inner and outer sleeves being cocentrically superposed enabling axial slide movement, the respective outer ends thereof being formed integrally with corresponding connecting passage ends in a leakproof manner, and each ends of the cylindrical resin film being connected in a leakproof manner to a portion of the connecting passage end region and a portion of the inner and outer sleeves respectively, the portion being other than the regions allowing mutual slide movement of both sleeves, the cylindrical resin film being arranged to cover the gap between the inner and outer sleeves. According to this example, at least one of the inner or outer sleeves may be formed to function as the corresponding connecting passage end region.
The mounting of the cylindrical resin film is carried out either by welding or bonding the end of the cylindrical resin film to the connecting passage end, sandwiching the end of the cylindrical resin between the passage end region and an adjacent piping flange, welding or bonding the end of the cylindrical resin to the inner or outer sleeve, or a combination of the above.
Actually, a flare region formed to at least one end of the cylindrical resin film can be sandwiched between and fixed to the corresponding connecting passage end region and a connecting body such as a piping adjacent to the end region. According to this structure, there is no need to weld or bond the cylindrical resin film, and assembly or maintenance of the device is simplified.
At least one of the inner or outer sleeves can be formed to function as a connecting passage end region without being formed separately from the corresponding passage end region, or in other words, the connecting passage end region may be structured to form at least one of the inner or outer sleeves.
Similarly, at least one end of the cylindrical resin film can be fixed integrally to the inner surface of the inner end region of the inner or outer sleeve in a leakproof manner.
When a flare region is formed to at least one end of the cylindrical resin film, the flare region can be formed a bolt inserting hole, and if the connecting passage end region and the connecting body such as a piping adjacent to the end region is connected by a fastening member including a bolt-nut, the bolt can be penetrated through the bolt inserting hole in order to provide a pretension in the axial direction to the cylindrical resin film.
Thereby, when the flare region is pulled into the inner direction, the bolt inserting hole of the flare region is supported by the bolt and prevents loosening of the cylindrical resin film.
The connecting passage end region and the connecting body such as piping adjacent to the end region can be connected together by a screw union joint structure. In this case, the flare region can be provided in advance with an expanded region that fits to a groove formed in advance to the connecting passage end region in the connected state, and thereby provides pretension in the axial direction to the cylindrical resin film.
There are cases where it is preferable to apply highly elastic resin for the cylindrical resin film. For example, product name xe2x80x9cST siliconxe2x80x9d manufactured by K. K. Shibata Kogyo-sho is remarkably advantageous in tensile strength, tear strength, elastic elongation limit, durability and so on compared to the general-purpose silicon, and the material is hygienically safe for application to food industry, so it is appropriate for application to food and beverage fluid or electronic component fluid that need hygienic environment and fluid quality maintenance.
Moreover, an air hole is formed to the connecting passage end region for releasing the space formed between the expansion outer cylinder and the cylindrical resin film to the atmosphere. Thereby, the space is ventilated to outer air, and the pressure within the space will not be increased. Further, when the cylindrical resin film may break and inner fluid leaks out to the space, the fluid leaks out of the device through the air hole, and contributes to early discovery of the generation of such abnormal condition and enables prompt correspondence to such situation. The air hole can be a valve.
A device for measuring strain can be mounted on the bellows-type outer cylinder, thereby notifying generation of abnormal strain and advising appropriate correspondence.
According to the present embodiment, the expansion joint device comprises a pair of flanges equipped to both axial ends of the device which also function as a fluid passage, a bellows-type expansion outer cylinder having both axial ends substantially fixed to the flanges and capable of expanding and contracting in the axial direction, and a cylindrical resin film arranged substantially cocentrically within the interior of the expansion outer cylinder, having both ends thereof substantially fixed to the pair of flanges;
wherein the bellows-type expansion outer cylinder comprises first flare regions formed to both axial ends of the bellows respectively, one of the first flare regions being substantially connected in a leakproof manner to the axial outer side surface of one of the flanges and the other of the first flare regions being substantially connected in a leakproof manner to the axially outer side surface of the other flange, further comprising reinforcement rings mounted to groove regions formed to the outer peripheral surface of the bellows-type expansion outer cylinder respectively; and
the cylindrical resin film comprises second flare regions formed to both axial ends thereof respectively, one of the second flare regions being sandwiched with pressure between one flange and a flange region of an axially adjacent passage region, and the other second flare region being sandwiched with pressure between the other flange and a flange region of an axially adjacent passage.
In this case, the bellows-type expansion outer cylinder can be made of polytetrafluoroethylene, and the bellows-type expansion outer cylinder may be equipped with low-hardness elastic resin filling rings filled to each of the groove regions formed to the inner peripheral surface thereof, respectively. The flange and the flange region of another passage adjacent to the flange can be connected by a bolt-nut-type fastening member, and the second flare regions of the cylindrical resin film can each comprise a hole through which the bolt of the fastening member is inserted, thereby providing pretension to the cylindrical resin film.
The present invention comprises the cylindrical resin film used in the above-explained expansion joint device.
The cylindrical resin film includes a cylindrical body disposed to the innermost space of the expansion joint device for defining a fluid passage; and
flare regions connected to both axial ends of the cylindrical body and extending in a disk-shape in the radial direction substantially orthogonal to the axis of the cylindrical body, each being sandwiched between the expansion joint device and another passage axially adjacent thereto.
The cylindrical resin film can be formed so that the expansion joint device and other piping and the like axially adjacent to the device are connected together by a fastening member including a bolt-nut, and the flare regions each comprise a bolt inserting hole through which the bolt is inserted in the connected state.
According to another embodiment, the cylindrical resin film can be formed so that the expansion joint device and other piping and the like axially adjacent thereto are connected together by a screw union joint structure, and the flare regions each comprise an expanded region that fits to grooves formed in advance to the expansion joint device and the other piping and the like.